Ball and socket joints of the type mentioned in the introduction are used, for example, but by no means exclusively, on the chassis of motor vehicles. Such ball and socket joints with pivoting angle sensor are used, for example, to detect the relative positions of different chassis parts in relation to one another or the relative position of, e.g., the vehicle axle and the vehicle body and measure them for further processing in an electronic system of the vehicle. This is significant in modern motor vehicles, for example, for electronic stability programs, automatic level control or for dynamic headlight leveling of headlight systems.
Both reliable and accurate detection of the angular position of the ball and socket joints with high repeatability and rapid dynamic response of the pivoting angle sensor are of great significance for such systems. Moreover, due to their arrangement in the area of the chassis, ball and socket joints of this class are, however, also exposed to extremely high mechanical loads, for example, due to vibrations, as well as to strong effects of environmental media, such as moisture, sand or de-icing salt. Nevertheless, users require long service life, fail-safe operation and elimination of the need for maintenance along with low costs.
To meet these requirements it has proved to be useful to integrate in such ball and socket joints systems for detecting the pivoting angle which operate in a contactless manner, especially on the basis of magnetic field effects. A permanent magnet is usually associated in this case with the joint ball, and a magnetic field sensor, especially of the magnetoresistive type (MR), is usually associated with the joint housing. An MR sensor changes its output signal as a function of the direction of the magnetic field lines passing through it, which predestines it for use for ball and socket joints with pivoting angle detection.
Such a ball and socket joint is known, for example, from DE 101 10 738 A1. This ball and socket joint has a bar magnet arranged in the joint ball as well as a magnetic field sensor fastened to the joint housing.
Because the arrangement of such ball and socket joints with pivoting angle detection is different practically in each type of vehicle or because of different chassis geometries or as a consequence of the different designs of electronic control systems, such as headlight leveling or electronic stability programs, it is, however, necessary in most cases to design such ball and socket joints in a vehicle-specific or application-specific manner. The reason for this is that to achieve the highest possible accuracy of the angle detection, the entire measuring range of the magnetic field sensor should be utilized. This utilization of the entire measuring range of the magnetic field sensor should, however, be guaranteed independently from the value of the maximum pivoting angle or nominal pivoting angle occurring on the ball and socket joint.
In other words, this means that the combination of the joint ball, the permanent magnet and especially the magnetic field sensor must be dimensioned according to the state of the art specifically and especially practically for each application such that the amount of the change in the magnetic field passing through the magnetic field sensor is precisely such that the largest possible part of the measuring range of the magnetic field sensor is utilized when passing through the nominal pivoting angle of the ball and socket joint.
However, such an application-specific design of all the components of such a ball and socket joint, which determine the angle detection, is complicated and expensive. This applies especially to the adaptation of the placement, size, sensitivity and accommodation in space of the particular magnetic field sensor at the joint housing, which adaptation is necessary in the particular case.